1. Field of the Invention
This invention relates in general to advanced telephony services. In particular, the invention relates to a method for controlling the quality of service of a telephone call routed over an IP-based network.
2. Background Art
Recent years have witnessed a rapid convergence of voice, video, and data communications. Communication service providers have begun developing intelligent networks capable of seamlessly handling a multitude of data types. At the heart of such networks are advanced communication switches, such as the Lucent 5ESS, which are highly configurable and can support a variety of communications functions.
Traditionally, voice communications have been conducted over switched circuit networks with fixed, dedicated channels, whereby each active call has a predetermined bandwidth assigned exclusively thereto. Consequently, voice communications over such networks have been characterized by highly stable and reliable connections, with highly consistent sound qualityxe2x80x94attributes that users have often learned to expect.
By contrast, data communications are often conducted over packet-based networks, such as those based on the Internet Protocol (xe2x80x9cIPxe2x80x9d). Large numbers of users can share a common IP-based network because each user occupies network bandwidth only while actively transmitting information. However, due to the predetermined finite bandwidth of the packet network and a lack of reserved bandwidth for any individual user, IP-based networks typically possess a generally inverse relationship between the number of users actively transmitting data, and the maximum bandwidth available to each user. As network traffic increases, performance for each user typically declines.
As voice and data communications converge onto common networks, substantial advantages can be realized by routing voice communications over IP-based networks that have traditionally been used for data. The increased efficiency of an IP-based network will likely result in reduced infrastructure costs for a communications service provider, and accordingly may result in reduced cost to end users. Service providers who maintain multiple networks for different services may converge their services to one packet network, thereby potentially reducing the cost of network expansion and maintenance. Furthermore, corporations or other users who have multiple locations that are already connected by high-speed Wide Area Network (xe2x80x9cWANxe2x80x9d) data connections can leverage the existing data infrastructure to also route voice traffic over the WAN, thereby saving the cost of access fees otherwise incurred in routing calls over the public interexchange carrier network.
However, one challenge imposed by the routing of voice over packet-based data networks is ensuring a satisfactory Quality Of Service (xe2x80x9cQOSxe2x80x9d) for the voice communication. QOS typically refers to one or more of the following parameters: bandwidth, latency, jitter, and/or loss. Because users do not have dedicated channels allotted on a conventional IP-based network, quality of service over such a network can substantially degrade when network traffic is high.
Numerous problems can arise for many applications, including without limitation voice, facsimile transmission, or streaming video, when QOS is not controlled. Customers can become dissatisfied by a failure to maintain their expectations of highly stable and reliable service, and highly consistent sound quality, which expectations have been developed through years of using conventional switched circuit telecommunication systems. Moreover, many modern automated systems, such as voice mail and other telephone-based information systems, rely on voice and/or touch-tone digit recognition for data entry, option selection, and other operations. Such digit and voice recognition systems may fail or malfunction in the face of intermittent cut-outs or poor audio quality that can occur during high traffic periods on a conventional prior art packet network.
In view of the desire for a guaranteed minimum QOS over a packet network for applications such as voice, several methods and protocols have been developed to maintain predetermined minimum quality of service levels. Using such methods and protocols, different communication links can be assigned various QOS guarantees, thereby permitting the use of a common efficient packet-based network for many types of communications, without sacrificing reliable QOS for QOS-sensitive applications.
However, as QOS requirements increase, the cost of the communication in terms of network resources increases also. Therefore, when all or part of a packet-based communication is routed over a third party network, a higher price is typically charged for higher guaranteed QOS parameters. Even when a call is routed entirely within a single company""s network, there is a higher cost in terms of the company""s network resources for calls with a higher guaranteed QOS. Yet typical prior art QOS models contemplate assigning predetermined static QOS guarantees to each line of a communications system, regardless of the QOS actually required for any particular call. Such a QOS allocation will commonly result in inefficiencies, whereby a company pays the cost to access a high QOS line when it is not necessary, and/or alternatively suffers complications due to using a low QOS line when a higher QOS line would be appropriate.
Therefore, it is desirable, and an object of this invention, to provide a system with which a user can efficiently allocate appropriate QOS guarantees for communications placed over a packet-based network. It is also an object of this invention to allow users to provide a QOS authorization code, with which the user may, if authorized, specify a QOS guarantee different from any default line value that is appropriate for a particular call.
Finally, some call recipients may require or desire a predetermined minimum QOS guarantee for calls received, regardless of the line originating the call. For example, a voice mail system with touch-tone menu operation may have a specific QOS level that is required for reliable digit recognition. Therefore, it would be desirable if all calls placed to such a voice mail system were automatically assigned a predetermined minimum QOS guarantee that is known to allow for reliable digit and/or voice recognition. Accordingly, it is an object of this invention to provide a destination line override feature, whereby a call""s QOS can be automatically adjusted to guarantee predetermined QOS parameters corresponding to the line receiving the call.
The invention provides for the efficient allocation of network resources, when a packet network is utilized to route QOS-sensitive communications, such as voice, with specified quality of service parameters. Default quality of service parameters are assigned to a first telephone line on which a call is initiated. A dial code can then be received on the first telephone line. The dial code may include a security or personal identification sequence to restrict the specification of QOS parameters to desired users, and/or to log the use of specified QOS parameters. The dial code may also include a sequence which specifies one of a plurality of available quality of service levels.
A call is placed on the first line, directed to a second line. The applicable quality of service parameters for the call are then determined. If the QOS request code is valid, then the call is routed over the packet network with guaranteed quality of service parameters corresponding to the requested quality of service level. If the QOS request code is not valid, then the call is routed over the packet network with guaranteed quality of service parameters corresponding to the default quality of service level for the first telephone line. If sufficient network resources are not available to guarantee the requested quality of service level, the caller can choose to route the call at a lower quality of service level, or hold until the desired quality of service level becomes available.
Furthermore, a telephone line can be assigned override quality of service parameters, so that QOS-sensitive telephone users, such as voice mail systems that employ touch tone or voice recognition or individuals who demand high QOS, can ensure that all calls placed to them satisfy the override quality of service parameters. A call is initiated from a first telephone line, directed to a second telephone line, according to the quality of service level corresponding to the first line. The communications system determines that one or more of the first line quality of service parameters with which the call was initiated is of lesser quality that the level specified by the override parameters. The call is then routed between the first and second telephone lines with quality of service parameters equal to or better than the override quality of service parameters.